diff --git a/libkineto/src/CuptiActivityProfiler.cpp b/libkineto/src/CuptiActivityProfiler.cpp
index 41abef150..7d03505a0 100644
--- a/libkineto/src/CuptiActivityProfiler.cpp
+++ b/libkineto/src/CuptiActivityProfiler.cpp
@@ -1298,6 +1298,10 @@ void CuptiActivityProfiler::finalizeTrace(const Config& config, ActivityLogger&
   for (auto& session : sessions_){
     auto trace_buffer = session->getTraceBuffer();
     if (trace_buffer) {
+      // Set child start time to profiling start time if not set
+      if (trace_buffer->span.startTime == 0) {
+        trace_buffer->span.startTime = captureWindowStartTime_;
+      }
       traceBuffers_->cpu.push_back(std::move(trace_buffer));
     }
   }
diff --git a/libkineto/src/output_json.cpp b/libkineto/src/output_json.cpp
index 41b38499e..a3e30ebf8 100644
--- a/libkineto/src/output_json.cpp
+++ b/libkineto/src/output_json.cpp
@@ -233,8 +233,10 @@ void ChromeTraceLogger::handleTraceSpan(const TraceSpan& span) {
   }
 
   uint64_t start = transToRelativeTime(span.startTime);
-  uint64_t dur = span.endTime - span.startTime;
-
+  
+  // If endTime is 0 and start time is non-zero, dur can overflow. Add
+  // a guard to prevent this.
+  uint64_t dur = (span.endTime == 0) ? 0 : span.endTime - span.startTime;
   // clang-format off
   traceOf_ << fmt::format(R"JSON(
   {{
diff --git a/libkineto/stress_test/kineto_stress_test.cpp b/libkineto/stress_test/kineto_stress_test.cpp
index a258f1a65..ecf02adf2 100644
--- a/libkineto/stress_test/kineto_stress_test.cpp
+++ b/libkineto/stress_test/kineto_stress_test.cpp
@@ -29,6 +29,8 @@
 #include "kineto/libkineto/stress_test/tensor_cache.cuh"
 #include "kineto/libkineto/stress_test/utils.h"
 #include "kineto/libkineto/fb/nccl_profiler/NcclProfiler.h"
+#include <c10/util/ApproximateClock.h>
+#include <ApproximateClock.h>
 
 using namespace kineto_stress_test;
 
@@ -89,6 +91,8 @@ void read_inputs_from_json(std::string sJsonFile, stress_test_args *test_args,
 
 void trace_collection_thread(uint32_t trace_length_us,
   uint32_t cupti_buffer_mb) {
+  c10::ApproximateClockToUnixTimeConverter clockConverter;
+
 
   if (cupti_buffer_mb > 0) {
     // Configure CUPTI buffer sizes
@@ -111,6 +115,8 @@ void trace_collection_thread(uint32_t trace_length_us,
   auto& profiler = libkineto::api().activityProfiler();
   libkineto::api().initProfilerIfRegistered();
   profiler.prepareTrace(types);
+  auto converter = clockConverter.makeConverter();
+  libkineto::get_time_converter() = converter;
 
   // Collect the trace
   profiler.startTrace();